Directional aerial



July 10, 1945. P. P. GAMET 2,380,229

- DIRECTIONAL AERIAL Y Filed Aug. 19, 1942 3 Sheets-Sheet 2 //v 109v TO P/ERREPAUL G 5/- BYQQLQMS- ATTORNEY July 10, 1945. P.- P. GAMET ,3

' I DIRECTIONAL AERIAL Filed Aug. 19, 1942 s Sheets-Sheet s PIER/8E 2240/. 6mm: 7'

ATTORNEY Patented July 10,v 1945 DIRECTIONAL AERIAL Pierre Paul Gamet, Paris, France; vested in the Alien Property Custodian Application August 19, 1942, Serial No. 455,378 In France August 20, 1941 9 Claims.

The present invention relates to a directional aerial without a reflector as used, for transmitting or receiving more particularly short or very shorter even ultra-short waves by means of conductors traversed by progressive waves.

For this purpose it is known to provide aerials with four radiating elements or strands arranged in the form of a lozenge, two of the said radiating strands being connected each to a wire of the bipolar feeder while the two other radiating strands are connected with an impedance the value of which is equal to the characteristic impedance so as to avoid wave reflections The aerials of this type offer various drawbacks and more particularly the following:

The radiating diagrams of the said aeria comprise secondary follicles which radiate in a prejudicial direction; for this reason these follicles are troublesome and diminish the energy transmitted by the aerial in the preferred selected direction.

On the other hand it is very difiicult to obtain a radiating beam making a very small angle with the horizontal line in a vertical plane.

The present invention has more particularly for its object to remedy the said drawbacks in a certain measure and to reduce the secondary radiating follicles so as to" insure a higher energy in the preferred selected direction.

' An improved directional aerial permitting to attain the above mentioned objects presents the characteristic features which appear from the following description and more particularly from the appended claims.

Aerials according to the invention are shown by way of examples in the appended drawings in which:

Figure 1 is a diagrammatic representation showing the elements of my aerial with its feeding system.

Figure 2 is a diagram of the aerial showing the direction of .the currents flowing through the various conductors.

Figure 3 is a diagrammatic perspective view of my aerial.

Figure 4 is a three-dimensional polar radiation diagram of the aerial.

Figure 5 is a two-dimensional polar radiation diagram in a horizontal plane.

Figure 6 is a two-dimensional polar radiation diagram in a vertical plane.

Figures 7 and 8 show diagrammatically two forms of embodiment of the invention,

Figure 9 shows diagrammatically a composite array or net of aerials according to the present invention.

Figure 10. shows another composite array or net of aerials according to the present invention.

The aerial of the present invention (see Figures 1 to 3) is formed of a conductor I, 8 serially followed by a c0nduct0r 8, 9 itself serially followed in turn by a conductor 9, II). To the end In of this latter conductor is connected a terminating impedance H which is equal to the characteristic impedance of the aerial.

At the other end l2 of the said impedance is connected another conductor l2, l3, serially followed by a conductor l3, I4, which is itself followed serially in turn by a conductor [4, [5.

All these conductors may have any length, but

this length is generally equal to a wave length or to a multiple of the wave length.

The array of the said conductors with the characteristic terminating impedance ll forms a broken line having the form of a convex regular hexagon the extremities 1 and I5 of which are connected to the conductors l6 and ll of a bipolar feeder which connects the said aerial with the high-frequency generator I8.

This aerial operates in the followingmanner:

The generator l8 (see Figure 1) delivers highfrequency energy to the feeder l6, H, the characteristic impedance of which is equal to the impedance presented by the aerial between the.

points 1 and-I5. Thus, the attack of the aerial between thesaid two points in no way modifies .the operating conditions of the feeder.

The free end of this aerial! and I5 is closed across an impedance II which is a pure ohmic impedance equal to the characteristic impedance of the system. Under these conditions the aerial can be compared with a line of infinite length since at every point of this line the value of the impedance is always equal to the characteristic impedance.

Let l9 be a point of the aerial located at a distance a: from the point I.

In such a system the propagation is of the form Be t where P is the propagation constantvand B' an amplitude coefficient.

If E0 and I0 represent the voltage and the current respectively at the point of output and if I and V represent these same values respectively at a point of the line located at a distance X from the origin, one has I The value of the current I1 which flows through the conductor 1, 8, is given to a first approximation by neglecting the damping within the limits where the term 6* can be considered as constant in the following expression:

I =A sin 21r[% where T is the period or cycle, t

the wave length. i

Such a wave is a progressive wave characterthe time and X ized by an amplitude the effective valueof which. regularlydecreases along the line'and thephase duced by the currents I2 and I5 at a point M (see Figure 3) of zenith distance and of a colatitude is of the form:

sin[2% cos 0']] cos sin 0 sin 11:] KZI5 /lsin 0 sin (where K1 and K2 are two constants and where H is the effective height of an element).

The same would be true for the current elements I3 and I6 or I1 and It the effect of which would appear as .the cosine of the angle which they make with the elements I2 and I5.

If the point M is located in a plane perpendicular to the axis :v'v a: one will have =0 and the preceding equation will be reduced to E K I sin cos til-K 1 sin [2 cos 0] If the pointlvl is located at a comparatively great distance from the aerial one will have very nar1yK1I1=K2I5 and 0:6.

Accordingly, for all the points located in a plane perpendicular to the axis :1: w (i. e. the axis A A in Figure 2). the resulting radiation is nearly nil. The same is true for the axes B B and D D.

On the contrary, there is adding of the fields in the direction C C and thus a maximum radiation and no field at all in the direction'C C.

The form of the radiation in space is shown in Figure 14.

The plane of the aerial being horizontal, the radiation takes place in this plane in the direction 2 |-22. I

The maximum radiation angle in the vertical plane is shown by 'y.

Figures 5 and 6 show the polar radiation diagrams in the horizontal and in the vertical plane respectively.

In the horizontal plane about the radiation curve 23 there remain secondary follicles 24, 25, 26, 2'1, 28 radiating in undesired directions. But these follicles have onlya small amplitude with respect "to theradiationtcurve 23 and are considerably reduced 'with respect to those of the radiation diagrams'of the aerials.

In the vertical plane the radiation curve 29 is well as the width of the beam can be modified by adjusting:

(2) The length of the sides of the hexagon;

(3) The angles which the sides of the hexagon make with one another.

It is easy to increase considerably the field in thepreferred direction (while reducing the secondary follicles) by giving the sides of the hexagon values which are greater than two wave lengths or three wave lengths.

In this manner it is easy to obtain considerable gains of the order of 15, 20 and even 25 decibels in the preferred direction through the circular radiation which would be produced by a dipole energized under the same conditions.

This aerial which has been described offers numerous advantages and more particularly the following ones:

(1) First it has 'an excellent efficiency since the prejudicial radiations represented by the secondary follicles are considerably reduced.

(2) It is also very easy to modify the angle of inclination and the acuteness of the radiating beam and to obtain radiating diagrams showing great symmetry.

(3) The aerial has a fairly highaperiodicity, which permits to use it in devices with wide pass bands (transmission and reception of images in television) Numerous changes and modifications can be made in the above described device without departing from the scope and spirit of my invention.

The directional aerial can have the form of an irregular convex hexagon (Figs. 7 and 8) provided, however, that it has a perfectly symmetrical form with respect to the axes a: 0: (Figures I and 3), that is to say that the sides 4|, 42, 43 respectively must be parallel to thesides 44, 45, 43 respectively.

More particularly; the conductors 42 and 45 (Fig. 7) can be made longer than the othericonductors 4|, 43, 44 and 4B.

The said conductors 42 and 45 can also be made shorter than the other conductors 4|, 43, 44 and 46 (Figure 8).

V The sides of these hexagons may have any length whatever.

r The present invention also covers-nets or arrays formed by the grouping of a plurality of the preceeding aerials and permitting to obtain either a better directional efliciency or a betterpower efficiency. Y

The net or array shown in Figure Qisformed of four hexagonal aerials 5|, 5'2, 53-and 54 arranged symmetrically around the point '60 so that the axes E E and F F of the said aerial are perpendicular. A V

Each of these aerials 'isclosed across acteristic impedance 55, 56, 51, 58. The hexagonal aerials 5|, 52, 53 and 54 are connected with one another in the following manner:

. The output conductor 6| of the hexagonal aerial 5| is connected withtheinputconductor .61 of the hexagonal aerial] .52 the. output conductor 63 0f the aerial 52'is connected 'with'the input a charconductor of the hexagonal aerial 53 and so on,

the output conductor El of the last aerial 54 being connected with the input conductor of the first aerial The conductors which are connected to ether in this manner can form a single conductor, each of the conductor units 6! and 62, B3 and 54,135 and 56, 6'! and 68 having elements in common.

This arrangement offers the advantage that it permits to obtain a very sharp directional radia- It is used effectively in radio beacon systems.

. It is also possible to arrange aerials in a row (Figure 10) by replacing the haracteristic impedance of a first aerial by a second aerial the characteristic impedance of which is also replaced by a third aerial and so on.

Thus a series of aerials 3'5, 31, 33 (Fig. 10) is obtained which are connected in series, the first (36) of the said aerials receiving across its input terminals the energy supplied by the generator 18 through the wires It and I? of the feeder and the last (38) of the said aerials being closed across its characteristic impedance I I.

This arrangement ofiers the advanta e of diminishing the losses of energy in the terminal impedance since the first aerial instead of delivering into a non-radiating impedance delivers into a second radiating aerial which in its turn delivers and a feeding device connected with this hexagon.

2. In a directional aerial for transmitting or receiving electro-magnetic waves, three equal radiating conductors connected in series and making equal angles with one another, three other radiating conductors equal to one another and to the first three conductors and also making equal angles with one another, an impedance connecting together with each other each said unit of three conductors and thus formin a regular hexagon, and a feeding device connected With said hexagon.

3. In a directional aerial net, a first hexagonal aerial according to claim 2 a second hexagonal aerial the input of which is connected to the output of the first hexagonal aerial, a third hexagonal aerial the input of which is connected with the output of the second hexagonal aerial, a last hexagonal aerial the input of which is connected with the output of the preceding hexagonal aerial while its output is connected to the input of the first hexagonal aerial and a feeding device connected with said net.

4. In a directional aerial net, a first hexagonal aerial, a second hexagonal aerial identical to the first aerial and the axis of which is perpendicular to the axis of the first aerial, the input of this second aerial being connected with the output of the first hexagonal aerial, a third hexagonal identical aerial the axis of which coincides with the axis of the first aerial and the input of which is connected with the output of the second hexagonal aerial, a fourth hexagonal identical aerial the axis of which coincides with the axis of the third aerial and the input of which is connected with the output of the third aerial while its output is connected with the input of the first aerial, and a feeding device connected with said net.

5. In a directional aerial net, a first hexagonal aerial, a second hexagonal aerial mounted in the place of the impedance of the first hexagonal aerial, a third hexagonal aerial mounted in the place of the impedance of the second hexagonal aerial, a last hexagonal aerial mounted in the place of the impedance of the last but one hexagonal aerial, and a feeding device connected with said net.

6. In a directional aerial, an array of two groups each of three conductor elements and arranged substantially in the form of a hexagon With one element of each group substantially parallel to an element of the other group, a terminating impedance connected between the adjacent terminals of each of said groups at one end of said array and of value equal to the characteristic impedance of said array, and a highfrequency source connected across the adjacent terminals of each of said groups at the opposite end of said array, said elements being arranged symmetrically about an axis passing through said source and said impedance.

'7. An aerial as set forth in claim 6, said elements being of equal length and their array substantially constituting a regular hexagon.

8. In an aerial, a ring array of a plurality of an even number of antenna units, each of said units consisting of two groups each having three conductor elements connected in series, the elements of a said unit being arranged substantially in the form of a hexagon with one element of each group substantially parallel to an element of the other said group thereof, each said unit having a terminating impedance connected across the adjacent terminals of each of its said groups at one end of said unit and of value equal to the characteristic impedance of said unit, said units being arranged in a ring array with impedances on the outside of said ring and with the element of each group of each unit near the center of said ring, at the end thereof opposite its said impedance, being electrically in common with the adjacent element of the adjacent unit near the center of said ring and at the end thereof opposite the impedance of said adjacent unit.

9. In an aerial, a row array of a plurality of antenna units, each of said units consisting of two groups each having three conductor elements connected in series, the elements of a said unit being arranged substantially in the form of a hexagon with one element of each group substantially parallel to an element of the other said group thereof, a final one of said units having a terminating impedance connected across the adjacent terminals of each of its said groups at one end of said unit and of value equal to the characteristic impedance of said final unit, aid units being arranged in a row with said final unit at one end thereof, and with the adjacent terminals'of each group of adjacent units being connected together, the impedance of each said unit being equal to the characteristic impedance of the preceding unit more remote from said final unit, and a high-frequency source connected to the free terminals of the groups of the initial one of said units most remote from said final unit.

PIERRE PAUL GAMIB'I'. 

